PROJECT SUMMARY The United States continues to grapple with an unprecedented opioid overdose epidemic; there were more than 42,000 opioid overdose deaths in the United States in 2016. Despite significant national attention, funding, and mobilization of resources, the prevalence of opioid use disorder (OUD) and associated mortality rates continue to rise. We are in dire need of effective policy tools to curb this expanding epidemic. Medication-assisted treatment (MAT) with medications such as methadone or buprenorphine has been shown to be the most effective approach for treating OUD, but is widely underutilized. Increasing access to MAT is a key strategy in national efforts to combat the epidemic, which has led to recent federal policy changes. Specifically, in 2016, two policies increased the patient limit for MAT buprenorphine prescribing from 100 to 275 for qualified providers and allowed qualified nurse practitioners and physician assistants to prescribe the medication for MAT for the first time. However, the impacts of these policies are unknown. The proposed study aims to evaluate the effects of these two policies in the state of California with an interrupted time series design using several state-wide administrative data sources. Specifically, we aim to evaluate the policies' effects on the number and prescribing capacity of providers qualified to prescribe buprenorphine, actual buprenorphine prescribing, and opioid-related health outcomes, including hospital visits and deaths. Given the scale of the epidemic and the urgent need for expanded treatment availability, it is critical that we understand the effects of these policies so as to inform priorities and future strategies for connecting individuals to treatment. The proposed research makes highly cost-effective use of a diverse set of existing administrative data sources. Furthermore, the study will help to establish the impact, as well as the limits, of strategies that remove barriers limiting the supply and capacity of prescribers, and thus inform the need and development of parallel efforts addressing other barriers to wider buprenorphine utilization. The research will be conducted in parallel with a rigorous and targeted training plan under the mentorship of two eminent researchers and a statistical consultant. Through this research and training, the applicant aims to gain knowledge and skills to apply methods and tools from epidemiology, biostatistics, and other disciplines to the rigorous evaluation of policies, programs and interventions; to gain the capacity to make effective and innovative use of large administrative datasets to conduct applied opioid-related research; and to expand content expertise in the study of opioid use and related sequelae. All training and research will be conducted across the campuses of the University of California, Berkeley and the San Francisco Department of Public Health, which provide a combination of academic and applied research environments that is excellently suited for facilitating the applicant's development into an independent researcher.